I had a similar situation. We’d had an enormous fluffy male cat for about 1 year, then one night we brought home a little female kitten. Our huge tom was so taken with her that he was extraordinarily gentle and bathed her, let her climb him and snuggle him and she also rooted around on him, trying to nurse. He never took offense and just let her do whatever she wanted.

He’s still such a gentleman with her that during their evening feeding time, he steps away and lets her eat as much as she wants, then he’ll eat when he sees that she’s finished. And he still bathes her like he’s her momma. It’s an adorable relationship.